Continuous porcelain mill



Aug. 21, 1921;.

1,681,441 A. G. SHERMAN ET A1.

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A. G. SHERMAN ET AL CONTINUOUS PORCELAIN MILL Filed May 2l. 1925 11 Sheets-Sheet. 2

Aug. 21, 1928. 1,681,441

A. G. SHERMAN, ET 'AL CONTINUOUS PORCELAIN MILL Filed' May 21, 1925 11 Sheetssheet 3 9 (o l I Y L" f ATTORNEY.

Aug. 21, 1928.

1,681,441 A.l G. swam/1.11m ET AL cou'lnmousI PORCELAIN MILL 11 Shpetsvsheef 4 Filed May 21. 1925 Aug. 21, 1928.

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CONTINUOUS PORCELAIN MILL Filed May 21, 1925 11 Sheets-Sheet 5 my mm .0 /w

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Aug. 21, 1928.

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Aug. 21, 192s. 1,681,441

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A. G. #SHERMAN ET AL coNTINUoUs PORCELAIN MILL 1l Sheets-Sheet 8 Filed Mayzl, 19.25

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Aug. 21, 192s. 1,681,441

A. G. SHERMAN ET AL CONTINUOUS PORCELAIN MILL Filed May 21, 1925 11 sheets-sheet 9 A TTORNEY.

Aug. 21, 1928. 1,681,441

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CONTINUOUS PORCELAIN MILL Filed May 2l, 1925 11 Sheets-Sheet 10 e o oa uo ou A TTORNE Y.

Aug. 21, 192s. 1,681,441 L A. G. SHERMAN ET AL CONTINUOUS PORCELAIN MILL Filed May 2l, 1925 11 Sheets-Sheet 11 a f Z c, f 6

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,UNITED STATES PATENTl OFFIcE.

ALVIN o. SHERMAN AND ALBERT MEADOWS, or. DETROIT, MICHIGAN, AssIGNons To DETROIT VAPOR sTovE COMPANY, or DETROIT, MICHIGAN, A CoaronATIoN or MICHIGAN. l

`oONTINIrOUa PORCELAIN MILL.

Applicatiortniea May 21,1925. serial Na. 31,811.

This invention relates to a continuous mill for glass=enameling metal articles.

- We use porcelain and glass-enameling as synonymous terms. It is the Object of the invention to kprovide a mill for continuously working on the varticle in predetermined time periods from the time'the process is first undertaken until it is nally finished'. The several instrumentalities are so co-Ordinated in capacity, speed and distance of travel that they all Work together to apply the several coats of glass'enamel to the article as it. travels through the line of instrumentalities.

It is the usual practice in appl ing porcelain to sheet metal articles, suc as stove plates and the like, to perform the several operations separately. The metal has to be cleaned by giving'it several baths in clea-ninflr acids,such as acids for removing the grease and rust. The Work is then conveyed on trucks in stacked relation to a dip tank. Here they are dipped in the ground coat of porcelain, and this is usually also brushed over the plate so as to make sure'that the ground coat takes hold of the entire plate. The plates are then set upright and allowed to run and drip; they are then returned to the trucks and stored on racks. They are then taken olf the Y trucks and placed on a suitable carriage in large gangs and fed into a muiil'e furnace and heated until they are in a dull red-hot condition. This`is the firing Operation, which is in reality an intermittent operation; the work is loaded into the furnace in gangs, then left in the furnaces for a certain length of time and then removed. Also plates after being dipped or sprayed-With the ground or color coat, while awaiting to be fired are very.readi ly injured by Contact with each other. Then thev are taken out, transferred to the racks on the truck and leftto cool on these racks. These trucks Aare then wheeled to the spraying booths, the plates taken off andthe first white coat is sprayed on. They are again stacked onA the racks on the, trucks and wheeled to the edging department. This is an. Operation .for wipmg the white or color coat off along'the edges to prevent chipping in the finished product. The edged platesare then 'laid back in the racks and stored until they are tl 1oro1'1gh1yV dry. They are then `vals.

^again fed into the firing furnace in gangs on a carrlage. The same operations are're-r peated for the third coat. vNone of these operations, or at least most of them have no time regulation other than human timing, and no means is provided to assure a sequence of operation in regular Order on the individual units of work or at any certain time inter- Some of the racks may get side-tracked and left unnoticed for a considerable length ously undergoing theV several processes until they lissue as a linished product at the final end of the apparatus. Such a mill nicely controls all the time elements both of an operation and between4 operations.

By performing theseactions on the work Ain continuous succession, it is found that it saves almost a half of the cost of porcelain work, and italso does a much superiorgrade of Work, due to accurately controlling rthe time factorsboth in operations and between operations. This eliminates deterioration due to undesirable .physical and chemical changesgsuch as moisture content, dust, lack of or eXcessof drip, too little or too great fusion in firing, excess or too little acid in cleaning, etc.

Reference is made to our co'pending case ofA even filing date, Serial No.4 31,810, in which i the process is claimed.

In the drawings: e Fig. 1 and Fig. l are two portions ofone diagrammatical view of the entire instal1a" Fig. 2 is a diagrammatical side view, spli up inthree parts, showing the cleaning apparatus.

Fig. f8 is a fragmentary side elevation of 'the conveyor for the cleaner apparatus.

Fig. 4 1s a detail in perspective of one of the conveyor rods.

Fig; 5 is a section on the line 5-5 of Fig. 3.

' Fig. 6 is a section on the line 6 6 of Fig. v3.

Fig. 7 isa section on the line 7-7 0f Fig- (i.

Fig. 8 is a section on the line 8 8 Of Fig. la.

Fig. 9 is an elevational view of the parts shown in Fig. 8, taken from the right of Fig. 8.

Fig. 10 is a vertical section through one of the firing ovens.

Fig. 11 is a detail of the revolving floor of the oven.

Fig. 12 is a plan view of the furnace.

Fig. 13 is a perspective view of the dipping tank, showing the relation of the conveyor therewith.

Fig. 14 is a perspective of the spray booth showing the conveyor passing therethrough.

Fig. 15 is a front elevation of the cleaning apparatus showing how the work may be loaded onto the conveyor.

Now referring to Figs. 1 and 1, which should be read together, the whole installation will be seen in plan or diagrammatic view. The first instrumentality is the cleaning instrumentality. Now referring to Fig. 2. which should be read beginning the upper left hand corner, this is a conveyor of the chain type, the chain being designated a. This is provided with a plurality of transverse rods b. Over these are the hooks c, which hook into the perforations in the corners of the plates lV, which indicates the work. Itis not necessary to give all the parts of this conveyor in detail as obviously the detail is not the essence of the invention. Suffice it to say that these plates are preferably carried in a plurality of lines (there being sometimes as many as twelve plates hooked onto each transverse rod; see Fig. 15). They are carried first into the cleaning tank containing an alkaline cleaning solution such as caustic soda, and which is at a boiling temperature, for removing the grease; it is then automatically lifted out and carried into the hot water rinsing tank. thence into the picklingtank, again into a rinsingtank, and finally into a mild caustic soda tank intended to neutralize the acid. After the work leaves the neutralizing tank. it is carried by the conveyor down over the steam coils Z for drying off the water. Preferably the skeleton structure that supports the cleaning conveyor is provided with tracks e. on which the rollers f of the transverse shafts b turn. The chain a works over the sprocket wheels g. One of these is shown in the left of Fig. 3; these can be adjusted by t-he screws 7L to adjust the tension. At the delivery end of the cleaning conveyor, a drive is provided by a motor M, located on the super-structure, with a suitable variable transmiion i. This permits the adjustment of the speed of the conveyor for a purpose shortly to be'described.

Now referring to the plan view of Fig. l and 1 again, it will be seen that thedelivery end of the cleaning conveyor is immediately adjacent the dipping tank. rPhe work is .Figs 8 and 9.

taken off the cleaning conveyor, preferably by an operator who dips the plates in the ground-coat tank. This ground coat is necessary in all porcelain work in order to make the enamel stick to the metal. It contains a cobalt oxide which makes the ground coat a blue coat. It is not only desirable to dip the plate into the tank, but it is found preferable to also brush the ground coat liquid over the plate on both sides so as to assure its sticking to the plate. This could conceivably be done by n'laehinery, but it is found cheaper and more effective to have it done by a human agency. Another advantage is that the operator can inspect the work and return defective plates. One or two operators can take the plates as they come from the cleaning conveyor, and dip and brush them with the ground coat.

The plates are then set on the dripping and drying conveyor' that runs immediately above the dipping tank. The specific details of this conveyor are not essential to the invention', but one advantageous form is portrayed in A chain 7' runs over the sprocket wheels c. This is provided with depending easels m formed by suitable frames or brackets. The top of the chain is provided with yokes n on which are supported trolley wheels o, which run on the I-beam track 72. Any one of these sprockets can be the driving sprocket and connected with a Reeves variable speed transmission and a motor. This is simply one of the preferred forms of providing a controllable and variable speed drive ,for this conveyor. This conveyor, it will be seen from the diagrammatic view 1, takes the work when it is set on the easel and runs it for a short run on the outside of the driving chamber. This may be termed the dripping operation. The ground coat will, of course, run after the dipping operation, and this amount of travel permits all the excess to drip of,but not too much to drain off before it becomes immobile due to the application of the heat of the drying chamber'.

The drying chamber 100 is a brick enclosure. preferably kept at Q00 degrees Fahrenheit, by steam coils. The conveyor runs back and forth several times through this drying chamber. There are four runs of the leonveyor shown in the drying chamber, preferably about 308 feet of travel. The speed and the distance of travel through the drving room is so regulated that when the conveyor with the easels and the work issues out of the drying room, the plates are substantially drv. It is preferred to give the drying rooins :in excess drying capacity so that the speed may be varied, depending upon the class of work going through, and different furnace speeds.

The conveyor then runs across the mouth ot' thefirstfiringfurnaceF. This furnaceispreferably a circular conveyor type of furnace. It

is made circular so that it can have a continuously moving platform for carrying the work in progression through the firing area. The details of this furnace might be varied within side limits. However, in Fig. a suitable furnace for this purpose is shown. This comprises a suspended circular platform g, which is/supprted from the thrust bearing 7' by means of the suspension rods s. Upstanding from this circular platform are a plurality of posts t, which support the ring-like frame. work u, which in turn supports the pincarrying-bars w. These pin-carrying bars form a surface on which to lay'the work. This ring-like carrier rotates in the annular furnace chamber fv, which is constructed of suitable fire brick. Electric resistance heating elements 1/ project into the furnace chamber and are located immediately above the ring-like carrier.

An operator takes the plate with the dry ground coat off the conveyor as 1t passes 1mmediately in front of the furnace and passes it through the opening a into. the furnace. It then rotates upon the ring-likecarrier 1n the furnace and is exposed to the intense h eat of the electric resistance elements which maintain a uniform temperature in the furf nace. This is regulated so that in the furnace the heat approximates 1600 degrees Fahrenheit. The ring-like carrier is driven by a pinion 1, meshing with the large ring gear 2.

1 revolution every 21/2 minutes. i Preferably the heating elements are not located in the furnace at the doorways. This makes the heat in front of the furnace tolerable to the workmen. c

The enameled plates or articles rotate slowly through the heated areas of the furnace until they come to the opening 3, where the same workman, or another, using a long fork, lifts the redehot plate off the prongs of the carrier and places it on the conveyor 4. This is provided with casels precisely like the conveyor in the drying chamber, which has already been described. This transfer from the drying. chamber conveyor to the furnace, and from the furnace to the coollng-sprayingdrying room conveyor could, of course, be accomplished automatically by machinery, but the complications andthe expense are such that the same can be more economically and better performed by human agency. In addition, it is preferable to insert the human agency at this vpoint for improperlycoated plates can be detected by the operator and returned for a new coat before being fused in the furnace.v It would be more difficult to reclaim bad plates after firing.

' Here tmay be Well to explain' how these several elements are all co-ordinated together Y desirable to run the-cleaning conveyor at.

very much reduced speed in or er to permit the articles to remain in the various tanks :D longer periodt Hence the speed of the cleaning conveyor 1s only about one-half or less of the speed of the dripping and drying c0nveyor. The 12 or less lines of the articles are simultaneously carrled by the cleaning conveyor so as to co-ordinate its capacity exactly with that of the dripping and drying conveyor.

Now in order to exactly prepare the cleaning apparatus for, the dip tank, after the plates have gone through the various tanks, they go through a warming zone foruforcing and insuring the drying (irrespective of atmospheric condition) so that when they are `delivered at the delivery end of the conveyor they will be in exactly71 the right shape to go through the dipping operation.

After the dipping operation, the conveyor circulates outside of the warming oven just long enough to permitthe flow of the excess of the ground coat on the plates and the dripping off of the excess before the coat is presented tothe heat of the drying oven, which is calculatedto give the vcoat a temporary ixedness by evaporating the volatile content of the ground coat. After passing through the drying chamber, the conveyor carries the work directly to the firing furnace.

Here it may benoted that the'speed of this drying conveyor and the longevity of travel through the drying conveyor is not only coordinated with the cleaning apparatus but also with the furnace. The drying operation at 200 degrees F. takes much longer than the firing operation. For instance, there is approximately 303 feet of conveyor in the drying room, traveling at an average speed o f about 20 feet per minute. This means that the article is in the drying room over 15 minutes; it is then conveyed directly to the furnace. The average speed of the furnace carrier ring is about 1 revolution irl/2% minutes;

hence the articles in the furnace are in about one-sixth of the time that they are'in thedrying room. This longer period in the drying room is secured not by slowing up the conveyor but by simply lengthening out the path of travel of the conveyor by doubling back and forth. Therefore this delay in the drying room does not 4interfere with the supply of work' to the furnace. Thedrying room simply is loaded up with a larger number of articles and have a longer path of travel than is the case with the furnace. but the conveyor speed is such as to supply the capacity of the furnace. The per-foot travel of the furnace conveyor does not have to be exactly that of the supplying conveyor or the take-away conveyor for the reason that the work can be laid closer together on the ring carrier of the furnace than is permitted by the fixed easels on the other conveyors-or if the ring conveyor is wide enough and the articles narrow enough, they can be arranged in a double line on the conveyor, thereby increasing its capacity for its speed. The essential feature, however. is that the furnace b e ahle in a giventime unit to handle the same number of work units as the several conveyors. It is more economical to -work the furnace at aA full capacity.

This coordination of capacity of each of the conveyors in a given unit insures a continuous mill operation, which is the objective of this invention. Inasmuch as the time of immersion in a bath, the time required for dripping, for drying, and for firing are all variant, this has to be coordinated by either varying the length 0f the path of travel as with the warming chamber and the dripping run, or the number of articles handled simultaneously as with the cleaning instrumentality, or the spacing of the articles in succession, as in the firing furnace.

These modifications can all easily be made so as to vary the time factor according to the needs of cach operation, and yet in no way interfere with the continuous progression on schedule of the work from its raw state to its finished condition. On the other hand, these time factors are also scrupulously worked out so that the application of any operation is no longer than is absolutely required. In this way the storage of the article while awaiting any of the porcelain operations is absolutely eliminated. There are two purposes which make it desirable to eliminate storage. One is that the storage involves increased plant investment in space, and also requires trucking and handling; and the storage involves the exposure of the work to atmosphere longer than is necessary, or allows the work to be fed to the next operation prematurely.

Another factor that must be borne in mind is that when each one of these instrumentalities has been properly adjusted or attuned to perform its function in the continuous mill operation, it becomes determinative of the conditions to which the work is exposed, so as to almost completely eliminate the human factor in securing uniformity of product. For instance, the bare plates are exposed for just a given time in each tank, and are in no way dependent on the workmans attention in taking them out. The dipping and scrubbing action must go on at a predetermined speed in order to keep up with the easels as they come along the dripping and drying conveyor. The dripping action is prolonged just a defined time before the heat of drying is applied. The drying 'action is applied at a precisely uniform time on each piece of work, and as each piece of work passes through identically the same source of heat, they are bound to be absolutely all uniform. The firing time is also uniform for every article, and the human factor is completely eliminated in this important operation, provided the workman takes the work out when it comes around to the delivery opening.

The firing operation is not a baking operation but a fusing one, as the temperature is very high- 1G00 degrees F., and the metal and the porcelain are heated to a dull red heat. This results in a fusing of the glass in the metal or the porcelain, to make a hard vitreous, almost non-scratchable finish.

After the plates `have been taken ofl' the furnace floor with forks, they are laid on the next conveyor, which is the cooling-sprayingdrying conveyor, designated 4. It will be noticed that this conveyor has a large number of runs outside the drying chamber 5, preferably about 160 feet. This is the travel necessary at the scheduled rate of the work through the mill to properly cool the work as it comes in the red hot condition from the furnace. The conveyor then runs through the spray booth 6, where a sprayer with spray guns of the atomizing type, sprays the work running on the conveyors with the first coat of white enamel; this is white glass enamel, or porcelain.l The work then continues on through the drying chamber, where within the best calculations just the right amount of travel to properly dry the coat is had. lVe have found in our work so far that this conveyor should be approximately 55() feet long at the average speed that we operate the conveyor, at about 20 feet per minute.

The 'work then passes by an edging wheel. Here, one or more operators temporarily take it off the conveyor and subject it to the high speed revolving brush, which wipes off the first white enamel coat along the edges. This is usually done with the aid of some kind of a pattern to cover up the major portion of the enamel coat. This is an old operation. and is found desirable in all porcelain work to prevent the white coat reaching out the cxtreme edge where it would be easily chipped.

The work is again replaced on the traveling easels and the conveyor loop runs in front of the second furnace F1. which is the first color coat firing furnace. Precisely the same op eration in the firing furnace occurs as with the first furnace. except that preferably, the temperature of this furnace is somewhat less than the previous one, viz about degrees Fahrenheit. It is usual to add a third coat or a second enamel coat to all porcelain work,

fit1

uis about 130 feet in length.

consequently a second cooling. run ofconof instrumentalities and even some vof the veyor, a second spraying booth, and a second separate instrumentalities 'themselves in so drylng chamber are all Vprovided and clearly far as the same are novel. v

shown in Fig. 1, of the drawings. The oper- In the claims, the secondand third coats atlons are precisely the same, andthe work are called the color coats, and of course has to also betemporarily taken Off the con. f-Whitef is considered a color; The first coatv veyor to be given an edging operation, It, is 1 s designated the ground coat; In some of then finally fired in the furnace-F2, and then the claims reference is made to the ground laced upon the final cooling conveyor, which 09M applying and tleatillg; thS S the ,dip-

pmg and dripping-and/or the drying opera- It will be understood that each of these tlOIlS- conveyors are driven by a variable speed mo- What Weelaim SI tor or power transmission, preferably an in- 1- 111 an apparatus for the Continuous dividua1 motor -With a Reeves variable enameling of metallic articles, a firing furspeed transmission. Hence, it is possible to 11u06 Provided With a CIltnuOuSly moving.

vary the speed of any of the eonveyore, but carrier, separate means for treating articles ofcourse, it; will also bef necessary, if one `to be fired including conveyors coordinated conveyr is varied in speed, that the speed of aS t0y Speed, Capacity and length of travel all the other oonyeyors be varied in Order to therewith to permit uninterrupted operation permit them to Coordinate, except ther, if, is of the furnace and to control the time element possible with someof the instrumentalities 0f eaCh treatmeutsuch as the furnace,andthefcleaning appara- 2. 111 an apparatus "for the continuous I ltus to vary the capacity, by either varying the cnameling of metallic articles, a firing furnumber of lines of work or varying the spa'enace provided with a continuously moving ing of the Work as if, is fed along These adcarrier, separa-te means for treating articles jnstments may be necessary where the appato be fired and for treating articles after they ratus is used on a different character of Work, are fired, including Conveyors @ordinated aS as for instance, different character of metals, t0 Speed, Capacity and length 0f travel there- -sults. Still again the second white enamel carrier, moans for cleaning and controlling such as castings instead of'sheet plates, or With, t0 permit uninterrupted Operation of different compositions of porcelain. Howthe furnace and to control the time element of ever, it may be necessary where quite radicaleaeh treatment t changes are needed in any one of the instru v 3- In auA apparatus for the continuous mentalities to reconstruct some of the conenameling ofvmetallic articles, a tiring furveyor lines in order to get the proper length nace provided With a continuously moving of travel to attune each instrumentality toits carrier, separate means for treating articles o eration, and its required speed withinthe to be fired and for treating articles after they continuous mill. are fired, including conveyors coordinated as It will be understood that the dimensions, to speed, capacity and length of travel theretime elements and s ciic character of the with, to permit'uninterrupted operation of various instrumentallties are simply given as, the furnace and to control thetime element of preferred constructions, or preferred direceach treatment, and also the time element betions with the experience that We have had at tween each step of the continuous operation this time. They are subject to modiiication ofthe apparatus. within wide limits, without departing from 4c. In an apparatus for -the Continuous the spirit of,our, invention. enameling of metallic articles, a firing fur- It will also be understood that partial connace provided with a continuously moving tinuous porcelain mills could be utilized With carrier, and separate, dripping and drying measurablygood results. For instance, the instrumentalities for treating articles to be entire cleaning instrumentality as an autofired, including conveyors coordinated as to matic feature could be eliminated, and this speed, capacity and length of travel relative be done according to the old practice, but of to the firing operation to control the time course, with not as good results. So too, the" element of each treatment. drying-dipping-drippin apparatus could be 5. In an apparatus for the continuous eliminated as part of t e continuous mill, enameling of metallic articlesa,firing furl but of course With still less advantageous renace provided lwith a continuously moving operation could be completely eliminated, or the applying of the ground coatto the articles could be performed as it has always been per- Ato be red, including conveyors coordinated formed in the past. Also the edging operaas to speed, capacity and length of travel tion could be eliminated but with not very therewith to permit the correct and uninterrupted operation of the furnace and to control the time element of and between each treatment. f

practical results. A

We refer to this simply to show that We regard our invention to embrace not only the comprehensive continuons' porcelain mill described, but also somev of thesubcombinations 6. In an apparatus rfor the continuous l enameling of metallic articles, a ring fu\rnace provided with a continuously moving carrier, means for cleaning and controlling the applying of the ground coat to the articles to be fired and for cooling after they are fired including conveyors coordinated as to speed, capacity and length of travel therewith to permit the correct and uninterrupted operation of the furnace and to control the time element of and between each treatment.

7. In an apparatus for the continuous cnameling of metallic articles, a firing furnace provided with a continuously moving carrier, means for cleaning and controlling the applying of the ground coatto the articles to be fired and for effecting the cooling, color coating and second tiring including conveyors coordinated as to speed, capacity and length of travel therewith to permit the correct and uninterrupted operation of the furnace and to control the time element of and between each treatment.

8. In an apparatus for the continuous enamcling of metallic articles, a firing furnace provided with a continuously movin 1r carrier, means for effecting applying and drying of the ground coat before firing and for cooling after firing, including conveyors coordinated as to speed, capacity and length of travel therewith. to permit the correct and uninterrupted operation of the furnace and to control the time element of and between each treatment.

9. In an apparatus for the continuous enameling of metallic articles, a firing furnace provided with a continuously moving carrier, and separate dripping and drying instrumentalitics for treating articles to be fired and cooling, color coating and drying inst-rumentalities for treating articles after they are fired, including conveyors coordinated as to speed, capacity and length of travel relative to the firing operation to control the time element of each treatment.

10. In an apparatus for the continuous enameling of metallic articles, firing furnaces provided with a continuously moving carrier, ground coating instrumentalities for treating articles before first firing and color coating instrumentalities for treating articles after firstand before second firing, including conveyors coordinated as to speed, capacity and length of travel relative to the firing operation to control the time element of each treatment.

In testimony whereof we have affixed our signatures.

ALVIN G. SHERMAN. ALBERT MEADO'WS. 

